One persons worst 3 games might be another gamers favorites.
My games that I remember being bad are:

Syndicate EA Games remake. The Original Syndicate on Amiga was one of my favorite games of all time, and EA games comes and makes this piece of crap
Tera Online (for some reason i really hate that game on so many level :P )
WOW Cataclysm. (made me quit the game after having played it since early Classic )

There was so much hype for this game, so much innovation, the game that was gonna change everything, Will Wrights initial demo at the GDC conference was amazing, then you slowly started seeing the EA coming through, starting to make it more kid friendly, suddenly you had all these bright colours and singing and dancing with creatures. It changed so much which led to Will Wrights eventual departure from Maxis in 2009.

The game had so much potential, and turned out to be pretty shitty. (The creature/vehicle/building creators were pretty fun though)

Anyway, if you don't already see where I'm going with this, allow me to spell it out: the only meaningful MMORPG "endgame" -- i.e., something novel to do after the progression process is over -- is that of the sandbox.

1. Assassin's Creed (the original game, not the series as a whole). I liked the combat, and the story was okay, but it was so freaking repetitive. After the 3rd kill, you realize you are just doing the same thing over and over, in a slightly different landscape. I got AC at release, and once I was finished, I was done with the series until about a year ago when I saw my friend playing Brotherhood and decided to give 2, Brotherhood and Revelations a try. Huge improvement.

2. Family Guy: The Video Game. Such bad depth perception.

3. The Sims 3. I just couldn't get into it. I'm not sure why. Maybe I was just burned out from Sims and Sims 2 (and their expansions) and Sims 3 didn't add enough to keep it fresh.

I'm tempted to add D3, but I honestly didn't have any real expectations for it anyway, so it wasn't really a letdown. I only got it because it came free with the Annual Pass, and only bothered playing it because of all the D2 love that goes around. Once normal mode was done, so was I.

1. Dragonball GT Final Bout. As a teen, the idea of a Dragon Ball Z fighting game was probably the coolest thing I could think of. There weren't any that had been made in English at this point, and playing a Japanese title required tweaking the innards of your Playstation and voiding its warranty. One of my friends looked up how to do it and there we were, playing a DBZ Fighting game. Queue extreme excitement. This game was awful. Among clunky fighting mechanics, it had "power battles" where you'd shoot an energy blast at your opponent and you had to furiously mash the "X" button as fast as you could and whoever pushed it the most won. Well, this kind of thing gets old really, really fast, especially when you can turn any energy blast shot at you into one of these "power battles". Against the computer, sometimes it required an inhuman amount of button presses that would literally wear out your arm. Crap game.

2. Cataclysm. Having been skeptical about it well before its release, I was very pleasantly surprised by all the cool stuff the beginning of Cata brought to the table. I found myself highly engaged and very entertained. Sadly, as the Xpac rolled on, mediocre tiers of content, not much reason to leave the cities, and horrid class and spec balance finally made me throw in the towel after 6 years of WoW. Never had I been so frustrated with WoW than during Cataclysm.

3. Yoshi Story. Yes, when I was a kid and saw this game in Nintendo Power I thought it was going to be really fun. This was the era of great platforming games like Mario 64/Banjo Kazooie/DK 64 which had been preceded by other great platforming games like Super Mario World/Super Mario World 2/Donkey Kong Country on the SNES. For some reason I thought I'd be able to spend as much time playing and completing this game as those, but was sadly disappointed. There was nothing to this game, and the only secret things I could unlock were a white and black Yoshi. Huge letdown, and a waste of my precious allowance.

The only objective way to determine success in a business is financially.

Then how are we going to measure financial success? Flat income? Compare it to budget? What about time spent creating it, is a 20-years-in-production-game selling just barely more than its budget a success?

Diablo 3 failed because Blizzard spun far too many features aimed at the game generating revenue after the box sale. Trying to make games generate money after their sales is a cancer on the game community, that has since destroyed expansion packs which were only ever successful if they delivered a satisfying amount of content. Blizzard have done expansion well before, D2:LoD, S:BW and WC3:TFT. This current money grabbing allows studios to charge premium amounts for trivial and terrible content.

Now Diablo 3 has the worst one of all. Giving the option and nigh on forcing people needing to spend real money on in game items needed ot progress through the game is just, bad. And that is why D3 failed. Also, playing through the same content 4 times...

Diablo 3, SWToR, and AION are all financially stable, profitable, and enjoyed by many gamers. As many as WoW or whatever you favorite game is? Maybe not, but that does not mean, at all, that it is a failure.

Anarchy Online had the worst MMO launch in history, and today is successful. SWToR isn't even a year old, and everyone still can't get over "ToRtanic". Maybe you need to get over your selves.

Diablo 3 was never going to be as good as Diablo 2, because that's how nostalgia works.

Seeing ppl list swtor as one of the top 3 game failures makes me sad :< i loved that game.. pvp was fun lvling was awesome flashpoints were fun.. proffesions were fun and not to grindy. Only - whould be the operations... i Most wholehartedly disagree with it being a top 3 game fail...

However. My 3 games whould be.

1. Diablo 3
Itemization.. droprates and ah ruined my game experience. I rather have a hard but rewarding game then an easy unrewarding one.. But in this case, it was either easy and unrewarding (on act 1-2) or hard and unrewarding (on act 3-4)...

2. Conan mmo
Sure it was beatiful and it had some nice story to it but.. it felt so so so unfinished.. several times during lvling you ran out of Quests to do and many of the instance bosses didnt even have abilities (or at elast they didnt use them...) more then autohit.. Outdoor instances was kinda broken, mob tagging bosses against 3-4 other grps was just annoying..

3. Dragon age 2.
The "lol" option in the dialogues kinda made the game feel very unserious.. and story sucked. Somehow the roleplay element wasnt there as heavily as it was in Origins.

hmm, ofc. If i compare any of the above 3 games to any of the fkn sportsgames that comes out every damn year they whould look like diamonds in a pile of shit. Its disgusting how much money the companies make from doing another NHL or FIFA every year that is pretty much the same with slighlty better grafics..

FF11 had a huge playerbase mostly in Japan, but many too in EU NA and Middle East, many of them tried FF14 on release and it was basically unplayable due to server issues for weeks, and even then the content and gameplay was so incredibly awful that almost no one could stand it.

It led to the concession from the Publisher that it was so awful that charging a fee to play would be immoral, the sacking/'re-placement' of the entire development team responsible who were all prominent long-term employees of the developer. After a new team was put in place the game was completely revamped and reimagined from start to finish as FF14 2.0 which may still not be finished yet, more or less 2 years after the initial release.

Diablo 3 (at least when it first came out. Although it's already burnt it's bridge for me even if they've fixed the problems with it now. I won't play it again.)
FF 14 - A company that has to apologize to it's playerbase for producing a crappy product is a tell tale sign of a fail game
Not sure what else I'd add.
Games I've been disappointed in would include: Aion, Dragon Age: Origins, WoW Cata/MoP and Oblivion but I wouldn't call any of them failures.

I'm excited about the upcoming TESO and honestly hoping no one calls it a WoW killer as that seems to be the kiss of death for new MMO's.